The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
Internal combustion engines are a popular form of energy production for automobiles and other vehicles. Generally, an internal combustion engine converts chemical power from fuel into mechanical energy to drive the vehicle. A typically four-stroke, spark ignition includes an intake stroke, compression stroke, power stroke, and exhaust stroke. The intake stroke includes drawing an air-fuel mixture into the combustion chamber. The compression stroke compresses the air-fuel mixture causing an increase in temperature and pressure within the combustion chamber. Next, the air-fuel mixture is ignited by a spark plug. The resulting explosion is the power stroke which generates the mechanical energy to drive the vehicle. The exhaust stroke expels the explosion exhaust gases from the cylinder.
The air to fuel ratio of the air-fuel mixture is a characteristic of an internal combustion engine that, in part, determines the power output and fuel economy of the engine. Specifically, the air to fuel ratio (AFR) is the mass of air per the mass of the fuel present in a combustion chamber during combustion.
Standard internal combustion engines operate all of the combustion chambers to generate a power output of the engine. To increase or decrease the power output of the engine, the air to fuel ratio of the air-fuel mixture is varied in the combustion chambers. Generally, the air to fuel ratio is varied between a lean mixture in which there is more air per mass of fuel and a rich mixture in which there is less air per mass of fuel. Lean mixtures provide less power but are fuel efficiency, while rich mixtures provide more power output but are less fuel efficient.
The internal-combustion engine offers a relatively small, lightweight source for the amount of power it produces. Additionally, internal combustion engines are generally reliable and cost effective to produce. However, the standard internal combustion engine generally has low fuel efficiency and high emission of pollutants.
Alternative engines have been developed to improve fuel efficiency and reduce pollutant emissions. For example, a hybrid engine combines a conventional internal combustion engine and an electric motor to generate power to drive a vehicle. While hybrid engine vehicles have higher fuel efficiency and lower pollutant emissions than a standard internal combustion engine, the hybrid engines generally generate less power output, are more expensive to produce and repair, and introduce new dangers in operation than the internal combustion engine.
Instead, the internal combustion engine can be improved for better fuel efficiency while also lowering emissions.